need the exact codes.. there are many for o2
sensor..
actually i will declare it is IMPOSSIBLE to trouble shoot with logic (the only kind that can work reliably in cyberspace).
The codes are very specific and trouble shooting is also technical and specific.. mechanics are all too quick to add an O2 sensor..
read here if you want some details..
I just threw a P0133 ..
http://www.bba-reman.com/content.aspx?content=NEXT_DTC_P0133_NEW_2